1. Field of the Invention
The present invention relates to airflow regulators for self-contained underwater breathing apparatus for underwater divers. Compressed air up to 4,500 pounds per square inch is contained in one or more tanks which mount on the back of the diver in a cradle which is secured by straps to the diver's body. The compressed air from the high pressure cylinder flows through a regulator assembly, to reduce the high pressure of the air in the tank to the ambient pressure surrounding the diver's lungs, making the air from the cylinder safe and breathable by the diver. The regulator provides the diver with air upon demand and automatically controls the flow of air to the diver.
There are several types of scuba regulators in use but they are differentiated by the number of stages and hoses utilized in their design. The stages of a regulator refer to the number of reductions in pressure that air stored in the diver's tank will experience before it is reduced to the ambient pressure of the diver's lungs. Most regulators currently in use reduce the air pressure in two stages through two separate mechanisms. The first pressure reduction is accomplished in a first stage regulator which is mounted on the tank and reduces the tank pressure to an intermediate pressure usually between 110 and 185 psi above the ambient pressure. A single relatively small diameter hose is connected between the first stage to a second stage regulator which further reduces the air pressure to ambient pressure. The second stage regulator is connected to the diver's mouthpiece and responds to the diver's need by providing breathable air reduced to ambient at the mouthpiece for inhalation by the diver. The flow of air into the mouth piece is intermittent and automatic in response to the diver's breathing and it can be triggered to free flow. Exhaled air is exhausted from the second stage regulator directly into the surrounding water.
More particularly, the present invention relates to an improved air flow adjustment mechanism for a scuba second stage scuba regulator, of the current design which is independent of the first stage regulator and is associated with the mouthpiece through which the diver receives the air from the tank.